As injuries pile up during an NFL season, the "next man up" philosophy is referenced frequently.
With the San Francisco 49ers top three cornerbacks out against the Atlanta Falcons in Week 9 – Tramaine Brock (shin), Kenneth Acker (concussion) and Keith Reaser (ankle) – Marcus Cromartie was that next man up.
Cromartie, who was called up from the team's practice squad the day before the game, started against the Falcons across from fellow corner Dontae Johnson. The third-year cornerback played 59 of the team's 64 defensive snaps and led the team with seven solo tackles.
"I just wanted to set the tone and show the team that they can count on me on every play," Cromartie said. "We all told each other before the game that we were going to have each other's backs, win, lose or draw."
Cromartie made his presence felt immediately in what ultimately turned into a 17-16 victory for the 49ers. On one of Devonta Freeman's first carries of the game, the corner shot into the backfield to tackle the NFL's leading rusher for a loss of four yards. The stop marked one of Cromartie's two tackles for loss in the game.
The former Wisconsin Badger also had one pass defended while he spent much of the game covering Falcons star receiver Julio Jones.
Cromartie credited his weekly preparation for his standout play. Despite being on the team's practice squad for the first eight weeks of the season, Cromartie knew his opportunity would come.
"I think that's what made me so successful," the cornerback said. "When I was on the practice squad, I didn't think of myself as a practice squad player. I considered myself a player who could get his chance to play."
Although he had been called up to the active roster on Saturday, there was still a good chance that Cromartie wouldn't make the 46-man gameday roster against the Falcons. All three of San Francisco's injured corners were going to test their injuries pregame to see if they could play.
None of them could.
That meant that Cromartie found out during warmups that he not only would be up for the game, but he'd be making his first career NFL start.
"Anytime you're getting your first start, whether you find out the minute before or 10 days before, I think it's a huge accomplishment and a huge milestone," Cromartie said. "I just wanted to go out and play my game."
Cromartie said that he carries himself with a chip on his shoulder.
Not just because of going undrafted in 2011, but because he shares the same last name with two other notable defensive backs: Dominique Rodgers-Cromartie and Antonio Cromartie.
Unlike Marcus, his cousins were taken in the first round and have made at least one Pro Bowl (four in the case of Antonio).
Marcus knows his climb to such success will be much more arduous.
"As an undrafted player, your opportunities are smaller than that of a first- or second-rounder," he said. "You've got to fit in where you get in and make the most of your opportunity."
And now Cromartie has earned his shot, he's got to continue to take advantage of it. He knows that Sunday was just the beginning of his story.
"It feels like I need to step up my game," Cromartie said. "I play with a chip on my shoulder and be like, 'When you hear Cromartie, let's hear Marcus and not so much Dominique and Antonio.' It lets me play with a little edge."